One other trick an IT person told me was if you catch something untoward going on was to immediately disconnect your computer from the internet, to stop the download, anf then do the search and destroy while not connected to prevent the virus from catching the action.
I use Spysweeper and even with updates occasionally get one that slips by. Send an email to their help line per their procedures and they have always given me a fix. If not something standard, often the fix is customized by their experts, and sometimes they give you outside source contacts (specific to the virus/malware) where you download a fix (sometimes requires going to multiple sites for a combined solution).
The other advise given where these viruses hide is correct also. The creatures creating the viruses are very creative, which requires constant updates to the program (I use automatic updates) and even then they get a step ahead which is why the companies like spyweeper have a method of you sending them the files, so they can learn and catch up.
They now have a feature which for a separate fee, you can have one of the experts on the phone to assist immediately, so that if the computer is business related or you need a fast fix they can assist you right away. But this isn't cheap,~$100. Otherwise it some times takes about 24 hours or less for you to get a reply.
Other sources offwer similar features and you need to find the one you like best and use it, and it isn't necessarily Norton or Macafee which have numerous compliants against them for all of the stuff they add and you cannot get rid of, sort of like compliants about AOL.
